THE CIRCULATION THROUGH THE LIMBS. 155 



THE CIRCULATION THROUGH THE LIMBS. 



By far the greater quantity of the blood, 50 to 70 per cent., lies 

 within the roomy reservoirs of the abdominal and thoracic organs. 

 Thence, by means of the vasomotor mechanism, the blood is distributed 

 at need to the locomotor organs. 



In the organs of locomotion the quantity of blood during rest has 

 been roughly estimated to be 36 per cent., and during activity 66 per 

 cent, of the whole blood quantum. 1 



Spehl reckoned the proportionate weight of each organ, washed free 

 of blood, to the weight of the whole body washed free of blood. He 

 likewise estimated the proportionate weight of the blood found in each 

 organ to the weight of the whole blood in the body. Dividing the 

 proportionate weight of the bloodless organ by- the proportionate weight 

 of the blood within it, he obtained the blood capacity of the organ. If 

 the blood were equally distributed throughout the parts of the body, the 

 blood capacity should equal 1. In the lungs he found the blood 

 capacity to be 11 to 13 in inspiration, 9 to 12 in expiration. The blood 

 capacity of the muscles was 0*327 to 0*343 during rest, and 0*520 to 

 0*664 during maximal activity. 2 



Chauveau and Kaufmann estimated the amount of blood flowing in 

 one minute through the levator labii superiohs of the horse to be five 

 times as great during activity as during rest of the muscles. 3 



The blood flow from the deep femoral vein of the dog during an epi- 

 leptic fit (excited by essential oil of absinthe) is three to five times as great 

 as during rest. 4 The clonic contractions alternately suck the blood into 

 the vessels of the muscles, and then compress the blood on into the veins. 



Similarly, massage greatly increases the flow of blood through the 

 muscles. Massage of a considerable muscular area produces a fall of 

 general arterial pressure, in consequence of the derivation of blood into 

 the dilated muscular vessels. This fall may amount to one-fifth of the 

 initial pressure. 5 



Graskell 6 observed the circulation in the mylo-hyoid muscle of the 

 frog directly, and measured the diameter of the vessels with a micro- 

 meter. On stimulating the trigeminus, the vessels dilated after a latent 

 period of 5 to 6 seconds. Venous congestion occurred only at the 

 commencement of tetanus, owing to the pressure of the muscle fibres. 

 During the rest of the period of excitation the blood flow was increased. 



In the curarised animal the outflow from the muscular veins of the 

 lower limb is increased on excitation of the motor nerves. Vaso-dilator 

 fibres must run, therefore, in these nerves. On the other hand, Graskell 

 obtained evidence of a diminished outflow on stimulation of the peri- 

 pheral end of the abdominal sympathetic in the curarised dog. We 

 must therefore admit the existence of vaso-constrictor fibres. They 

 are, however, but poorly developed in the muscles. 



At times of great muscular effort, a man closes his glottis, and main- 



1 Ranke, "Die Blutvertheilung und der Thatigkeitswechsel der Organe," Leipzig, 1871, 

 S. 69, 87. 



2 Spehl, "De la repartition du sang circulant dans 1'^conomie," These, Bruxelles, 1883. 

 '' Kaufmann, Arch, de physiol. norm, et path., Paris, 1892, p. 283. 



4 Hill and Xabarro, Journ. Physiol., Cambridge and London, 1895, vol. xvm. p. 218. 



5 Brunton and Tunnicliffe, ibid., 1894-5, vol. xvii. p. 362 ; Kleen, Skmvdin. Arch. . 

 Physiol., Leipzig, 1889, Bd. i. S. 247. 



6 Journ. Physiol., Cambridge and London, vol. i. p. 262. 



